1. Field of the Invention
The present invention relates to refrigerating engineering and more particularly to rapid-freezing apparatus for food-products.
The invention can be employed in the food industry and in agriculture for deep-freezing of food products, mainly fruit, vegetables, berries, partly prepared and ready-made food products.
2. Description of the Prior Art
Known in the art are rapid-freezing apparatus for freezing fruit, vegetables and berries (c.f. "Flofreeze", model M, Model W, in the catalog of Frigoscandia, Sweden), comprising means for conveying fruit, vegetables and berries to be frozen, an air cooler and fans mounted in the refrigeration chamber, as well as feeding and delivery means located outside the refrigeration chamber.
Also known in the art are rapid-freezing apparatus for partly prepared and ready-made food products (c.f. "Gyrofreeze" and "Cartofreeze" in catalogs of Frigoscandia, Sweden; "Automatic tunnel TD" in the catalog of Polimex-Cekop, Poland).
The latter group of rapid-freezing apparatus differs from the former one in the construction of the means for conveying product to be frozen.
Both groups of the above rapid-freezing apparatus offer refrigeration of a limited range of products. If it is necessary to freeze different kinds of products, the employment of said rapid-freezing apparatus entails considerably greater investments for their construction, a larger amount of production space and higher power consumption.
Well known in the art are rapid-freezing apparatus for food products suitable for deep-freezing both of fruit, vegetables and berries, and of partly prepared and readymade food products (cf. U.S. Pat. Nos. 3,169,381 and 3,982,404).
Said group of rapid-freezing apparatus includes ZFT-1 apparatus manufactured by Polimex-Cekop, Poland, and registered in the PPR Patent Office under Nos. NP-137, 734 and N20,578.
This rapid-freezing apparatus for food products comprises a refrigeration chamber accomodating means for conveying fruit, vegetables and berries to be frozen, means for conveying partly prepared and ready-made food-products, fans and an air cooler.
The means for conveying fruit, vegetables and berries is a two-section single-level screen conveyor. The two sections of said conveyer are arranged after one another, the velocity of the motion of the screen belts in the first section being higher than that of the screen belt of the second section located at the exit of said rapid-freezing apparatus.
The feed bunkers cooperating with and delivering products to the aforedescribed screen conveyer are located outside the refrigeration chamber.
Under said screen conveyor there are located ribbed-pipe air-coolers and fans providing air circulation. Alongside of the screen conveyer, throughout the entire length of the rapid-freezing apparatus, there extends a tunnel in which racks supporting partly prepared and ready-made food products are shifted manually. Said racks are rolled into the cooling chamber at one side of the rapid-freezing apparatus and rolled out from its opposite side.
The above rapid-freezing apparatus operates as follows. Fruit, vegetables or berries are loaded into the feed bunker and then distributed evenly over the whole width of the screen belt of the first section of the conveyor and fed into the refrigeration chamber. Under the action of the cooled air flow from below, the fruit, vegetables or berries get enveloped by the cooled air on all sides and form a fluidised bed on the screen belt.
The fruit, vegetables or berries are continuously agitated and frozen. The freezing process continues when the fruits, vegetables or berries are on the screen belt of the second section of the conveyer. Upon emerging from the refrigeration chamber, the frozen fruit, vegetables or berries are discharged into the delivery bunker.
Warmed up by the heat released by the frozen product, the air is sucked in by the fans and directed into the air cooler wherein it is cooled and fed again under the screen belt of said conveyer.
Partly prepared or ready-made food products are frozen in the following manner. The food products are placed on the racks whereupon the latter are rolled into the tunnel. When the tunnel is filled, the fans and air coolers are turned on, providing air circulation and thus refrigeration. When said products become frozen, the racks are rolled out from the tunnel. At this time the conveying means for fruit, vegetables or berries to be frozen is not loaded, and the cooled air passes freely through the screen conveyer.
The above rapid-freezing apparatus has a low efficiency when refrigerating partly prepared or ready-made food products because the charging of the product to be frozen and discharging of the frozen product is carried out intermittently, with cyclic recurrence of the operation.